This disclosure relates to refueling, and, more particularly, to refueling a hydrogen vessel.
Electrochemical cells are energy conversion devices, usually classified as either electrolysis cells or fuel cells. Proton exchange membrane electrolysis cells can function as hydrogen generators by electrolytically decomposing water to produce hydrogen and oxygen gases. Referring to FIG. 1, a section of an anode feed electrolysis cell of the prior art is shown generally at 10 and is hereinafter referred to as “cell 10.” Reactant water 12 is fed into cell 10 at an oxygen electrode (anode) 14 to form oxygen gas 16, electrons, and hydrogen ions (protons) 15. The chemical reaction is facilitated by the positive terminal of a power source 18 connected to anode 14 and the negative terminal of power source 18 connected to a hydrogen electrode (cathode) 20. Oxygen gas 16 and a first portion 22 of water are discharged from cell 10, while the protons 15 and second portion 24 of the water migrate across a proton exchange membrane 26 to cathode 20. At cathode 20, hydrogen gas 28 is formed and removed, generally through a gas delivery line. Second portion 24 of water, which is entrained with hydrogen gas, is also removed from cathode 20.
An electrolysis cell system may include a number of individual cells arranged in a stack with reactant water being directed through the cells via input and output conduits formed within the stack structure. The cells within the stack are sequentially arranged, and each one includes a membrane electrode assembly defined by a proton exchange membrane disposed between a cathode and an anode. The cathode, anode, or both may be gas diffusion electrodes that facilitate gas diffusion to proton exchange membrane. Each membrane electrode assembly is in fluid communication with a flow field positioned adjacent to the membrane electrode assembly. The flow fields are defined by structures configured to facilitate fluid movement and membrane hydration within each individual cell.
The second portion of water, which is entrained with hydrogen gas, is discharged from the cathode side of the cell and is fed to a phase separation unit to separate the hydrogen gas from the water, thereby increasing the hydrogen gas yield and the overall efficiency of the cell in general. The removed hydrogen gas may be fed directly to a unit for use as a fuel, or it may be fed to a storage facility, e.g., a cylinder or a similar type of containment vessel. A fuel cell system that uses containment vessels for hydrogen fuel storage needs a system and method for quickly and safely refueling those vessels when depleted of hydrogen fuel. Quick refueling operations are prone to significant heating, which can create difficulties in the refueling process.